scholarly journals Antagonism of phorbol-ester-stimulated phosphatidylcholine biosynthesis by the phospholipid analogue hexadecylphosphocholine

1993 ◽  
Vol 291 (2) ◽  
pp. 561-567 ◽  
Author(s):  
T Wieder ◽  
C C Geilen ◽  
W Reutter
Keyword(s):  
Cell Lines ◽  
Hela Cells ◽  
Mdck Cells ◽  
Fold Increase ◽  
Choline Uptake ◽  
Choline Incorporation ◽  
Contrast Enhanced ◽  
Phosphatidylcholine Biosynthesis ◽  
Membrane Bound ◽  
Stimulation Of

The antagonization of phorbol 12-myristate 13-acetate (PMA)-stimulated phosphatidylcholine (PtdCho) biosynthesis by the phospholipid analogue hexadecylphosphocholine (HePC) in MDCK cells was investigated and compared with the corresponding influence in HeLa cells. In both cell lines, PMA-stimulated PtdCho biosynthesis was antagonized by 50 microM HePC. However, subsequent experiments provided evidence that PMA enhances PtdCho biosynthesis by at least two mechanisms: (i) by stimulation of choline uptake and (ii) by translocation of CTP:choline phosphate cytidylyltransferase to membranes. In MDCK cells, 5 nM PMA caused a 4-fold increase in [methyl-3H]choline incorporation into PtdCho, which was paralleled by an approx. 2-fold stimulation of choline uptake. These data indicate that choline uptake might play an important role in the regulation of PtdCho biosynthesis in this cell line, especially since we could not detect any significant increase in membrane-bound cytidyltransferase activity in PMA-treated MDCK cells. In contrast, enhanced PtdCho biosynthesis in HeLa cells is achieved by a 2-fold increase in particulate cytidylyltransferase activity after PMA stimulation. Translocation of cytidylyltransferase from the cytosol to membranes is therefore important in HeLa cells. Nevertheless, in both cell lines, the main target of HePC seems to be the translocation process. In MDCK cells, addition of 50 microM HePC decreases membrane-bound cytidylyltransferase activity by about 45%, compared with control cells and PMA-treated cells. In HeLa cells, PMA-induced translocation of cytidylyltransferase to membranes is totally abolished by HePC.

scholarly journals Dengue Virus Induces the Expression and Release of Endocan from Endothelial Cells by an NS1–TLR4-Dependent Mechanism

2021 ◽  
Vol 9 (6) ◽  
pp. 1305
Author(s):  
Carlos Alonso Domínguez-Alemán ◽  
Luis Alberto Sánchez-Vargas ◽  
Karina Guadalupe Hernández-Flores ◽  
Andrea Isabel Torres-Zugaide ◽  
Arturo Reyes-Sandoval ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Mrna Expression ◽  
Cell Lines ◽  
Cell Activation ◽  
Dengue Infection ◽  
Elevated Serum ◽  
Fold Increase ◽  
Endothelial Cell Activation ◽  
Stimulation Of

A common hallmark of dengue infections is the dysfunction of the vascular endothelium induced by different biological mechanisms. In this paper, we studied the role of recombinant NS1 proteins representing the four dengue serotypes, and their role in promoting the expression and release of endocan, which is a highly specific biomarker of endothelial cell activation. We evaluated mRNA expression and the levels of endocan protein in vitro following the stimulation of HUVEC and HMEC-1 cell lines with recombinant NS1 proteins. NS1 proteins increase endocan mRNA expression 48 h post-activation in both endothelial cell lines. Endocan mRNA expression levels were higher in HUVEC and HMEC-1 cells stimulated with NS1 proteins than in non-stimulated cells (p < 0.05). A two-fold to three-fold increase in endocan protein release was observed after the stimulation of HUVECs or HMEC-1 cells with NS1 proteins compared with that in non-stimulated cells (p < 0.05). The blockade of Toll-like receptor 4 (TLR-4) signaling on HMEC-1 cells with an antagonistic antibody prevented NS1-dependent endocan production. Dengue-infected patients showed elevated serum endocan levels (≥30 ng/mL) during early dengue infection. High endocan serum levels were associated with laboratory abnormalities, such as lymphopenia and thrombocytopenia, and are associated with the presence of NS1 in the serum.

Proposed cytotoxic mechanisms of the saffron carotenoids crocin and crocetin on cancer cell lines

2014 ◽  
Vol 92 (2) ◽  
pp. 105-111 ◽  
Author(s):  
Se Hyeuk Kim ◽  
Jung Min Lee ◽  
Sun Chang Kim ◽  
Chan Bae Park ◽  
Pyung Cheon Lee
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Hela Cells ◽  
Human Cancer ◽  
Fold Increase ◽  
Cancer Cell Lines ◽  
Crocus Sativus ◽  
Cytotoxic Activities ◽  
Related Factor ◽  
Human Cancer Cell Lines

We investigated the cytotoxic activities of crocin and crocetin, 2 major carotenoids isolated from the stigma of Crocus sativus (saffron), on 5 human cancer cell lines and proposed their possible anticancer mechanisms. Crocetin, a glycosylated carotenoid, showed approximately 5- to 18-fold higher cytotoxicity than crocin, a carboxylic carotenoid (IC50 of 0.16–0.61 mmol/L for crocetin vs. 2.0–5.5 mmol/L for crocin). This suggests that structural differences account for the different efficacies between them. Fluorescence-activated cell sorting (FACS) analysis showed that crocetin induced a significant level of cellular reactive oxygen species (ROS) in HeLa cells, whereas crocin did not. This ROS induction supported the cytotoxicity of crocetin, but not of crocin. A significant activation of nuclear factor erythroid 2-related factor 2 (Nrf2) was observed in both HeLa cells treated with crocin and crocetin: a 3.0-fold increase by 1 mmol/L crocetin and a 1.6-fold increase by 0.8 mmol/L crocin compared to the control. Furthermore, both crocetin and crocin reduced the protein expression of lactate dehydrogenase A (LDHA), one of the targets for chemoprevention in cancer cells, by 34.2% and 10.5%, respectively, compared to the control in HeLa cells. These findings suggest that crocetin and crocin have different mechanisms for their observed cytotoxicity in cancer cell lines.

THE EFFECTS OF SULPHUR DIOXIDE UPON ESTABLISHED CELL LINES CULTIVATED IN VITRO

1962 ◽  
Vol 40 (2) ◽  
pp. 207-217 ◽  
Author(s):  
James R. Thompson ◽  
Donald M. Pace
Keyword(s):  
Cell Lines ◽  
Hela Cells ◽  
Sulphur Dioxide ◽  
Mouse Liver ◽  
Recovery Period ◽  
Inhibition Of Growth ◽  
Established Cell Lines ◽  
Established Cell ◽  
Stimulation Of

Studies have been made on the effects of SO2 and its salts on strain L, mouse liver, and HeLa cells. Of the cell lines tested, the HeLa cells seemed to be more sensitive to SO2 and its salts than the cells of mouse origin.Cells cultivated in "biological" medium grow in concentrations of gaseous SO2 up to 2000 p.p.m., although somewhat inhibited. Cells subjected to a concentration of 500 p.p.m. in this medium are not affected greatly and their growth is comparable to those cells in control cultures.The addition of various salts of SO2 (Na2SO4, Na2SO3, and NaHSO3) in concentrations from 10 to 200 mg% produced responses ranging from complete inhibition of growth (by 200 mg% NaHSO3) to apparent stimulation of growth by some concentrations of Na2SO4. Toxicity of these salts was in the order of NaHSO3 > Na2SO3 > Na2SO4.When cells in vitro are directly exposed to SO2 in specially designed culture flasks, strain L cells are apparently able to tolerate 5 p.p.m. SO2 for five 8-hour exposure intervals, provided a "recovery" period follows each exposure.Certain components of serum seem to play a very important role as protective agents in modifying the effect of gaseous SO2, possibly by combination.

Stimulation of renal phospholipid formation during potassium depletion.

1977 ◽  
Vol 233 (3) ◽  
pp. E212
Author(s):  
F G Toback ◽  
L J Havener ◽  
B H Spargo
Keyword(s):  
Potassium Depletion ◽  
Choline Uptake ◽  
Renal Cells ◽  
Renal Growth ◽  
Kennedy Pathway ◽  
Choline Incorporation ◽  
And Control ◽  
Choline Phosphoglyceride ◽  
Cortical Slices ◽  
Stimulation Of

Potassium depletion induces increased membrane phospholipid formation and renal growth in rats. To determine the mechanism by which potassium depletion augments phospholipid formation, the metabolism of radioactive choline, a precursor of choline-containing phospholipids, was studied in renal slices. Cortical and medullary tissue from potassium-depleted and control animals accumulated extracellular choline and sequentially converted it to phosphorylcholine, cytidine diphosphocholine (CDP-choline), and choline phosphoglyceride, thereby demonstrating that renal cells can utilize the Kennedy pathway for phospholipid synthesis. [14C]Choline uptake into intracellular fluid was increased in cortical slices from potassium-depleted animals. The apparent Km and Vmax of the kinase reaction which converts entering [14C]choline to [14C]phosphorylcholine were unchanged during potassium depletion. The rate of [14C]phosphorylcholine conversion to [14C]CDP-choline was also unchanged. In contrast, the Vmax of [14C]choline phosphoglyceride formation from [14C]CDP-choline was increased, whereas the apparent Km for this reaction was unchanged. These results indicate that increased renal choline phosphoglyceride formation during potassium depletion can occur via the Kennedy pathway and appears to be mediated by increases in choline uptake and the rate of CDP-choline incorporation into phospholipid, the first and last steps of the pathway.

Identification of lactate as a driving force for prostanoid transport by prostaglandin transporter PGT

2002 ◽  
Vol 282 (6) ◽  
pp. F1097-F1102 ◽  
Author(s):  
Brenda S. Chan ◽  
Shinichi Endo ◽  
Naoaki Kanai ◽  
Victor L. Schuster
Keyword(s):  
Carbon Source ◽  
Oxidative Phosphorylation ◽  
Hela Cells ◽  
Driving Force ◽  
Fold Increase ◽  
Lactate Exchange ◽  
Dose Dependent ◽  
Stimulation Of

We previously characterized the prostaglandin (PG) transporter PGT as an exchanger in which [3H]PGE2 influx is coupled to the efflux of a countersubstrate. Here, we cultured HeLa cells that stably expressed human PGT under conditions known to favor glycolysis (glucose as a carbon source) or oxidative phosphorylation (glutamine as a carbon source) and studied the effect on PGT-mediated [3H]PGE2 influx. PGT-expressing cells grown in glutamine exhibited a 2- to 4-fold increase in [3H]PGE2 influx compared with the antisense control, whereas cells grown in glucose exhibited a 14-fold increase. In the presence of 10 vs. 25 mM glucose during the uptake, there was a dose-dependent increment in [3H]PGE2 influx. Cis inhibition of [3H]PGE2 influx occurred with lactate at physiological concentrations (apparent K m = 48 ± 12 mM). Preloading with lactate caused a dose-dependent trans stimulation of PGT-mediated [3H]PGE2 uptake, and external lactate caused trans stimulation of PGT-mediated [3H]PGE2 release. Together, these data are consistent with PGT-mediated PG-lactate exchange. Cells engaged in glycolysis would then be poised energetically for prostanoid uptake by means of PGT.

THE EFFECTS OF SULPHUR DIOXIDE UPON ESTABLISHED CELL LINES CULTIVATED IN VITRO

1962 ◽  
Vol 40 (1) ◽  
pp. 207-217 ◽  
Author(s):  
James R. Thompson ◽  
Donald M. Pace
Keyword(s):  
Cell Lines ◽  
Hela Cells ◽  
Sulphur Dioxide ◽  
Mouse Liver ◽  
Recovery Period ◽  
Inhibition Of Growth ◽  
Established Cell Lines ◽  
Established Cell ◽  
Stimulation Of

Studies have been made on the effects of SO2 and its salts on strain L, mouse liver, and HeLa cells. Of the cell lines tested, the HeLa cells seemed to be more sensitive to SO2 and its salts than the cells of mouse origin.Cells cultivated in "biological" medium grow in concentrations of gaseous SO2 up to 2000 p.p.m., although somewhat inhibited. Cells subjected to a concentration of 500 p.p.m. in this medium are not affected greatly and their growth is comparable to those cells in control cultures.The addition of various salts of SO2 (Na2SO4, Na2SO3, and NaHSO3) in concentrations from 10 to 200 mg% produced responses ranging from complete inhibition of growth (by 200 mg% NaHSO3) to apparent stimulation of growth by some concentrations of Na2SO4. Toxicity of these salts was in the order of NaHSO3 > Na2SO3 > Na2SO4.When cells in vitro are directly exposed to SO2 in specially designed culture flasks, strain L cells are apparently able to tolerate 5 p.p.m. SO2 for five 8-hour exposure intervals, provided a "recovery" period follows each exposure.Certain components of serum seem to play a very important role as protective agents in modifying the effect of gaseous SO2, possibly by combination.

scholarly journals Phorbol myristate acetate stimulates [3H]choline incorporation into phosphatidylcholine independently of the ‘de novo’ pathway in Krebs-II ascitic cells: a unique effect of phorbol ester on choline uptake

1993 ◽  
Vol 293 (3) ◽  
pp. 739-744 ◽  
Author(s):  
H Tronchère ◽  
F Tercé ◽  
M Record ◽  
H Chap
Keyword(s):  
Endoplasmic Reticulum ◽  
Oleic Acid ◽  
Phorbol Ester ◽  
De Novo ◽  
Fold Increase ◽  
Subcellular Fractionation ◽  
Choline Uptake ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Choline Incorporation ◽  
Unique Effect

The effect of phorbol 12-myristate 13-acetate (PMA) on [3H]choline incorporation into phosphatidylcholine (PtdCho) and on the ‘de novo’ pathway of PtdCho synthesis has been investigated, compared with that of oleic acid, in ascitic-strain Krebs-II cells. Both compounds stimulated [3H]choline incorporation into PtdCho, but the PMA-induced incorporation was saturable at concentrations of the agonist around 100 nM, whereas no saturation was noticed with oleic acid up to 1 mM. Chase experiments showed no effect of PMA on the conversion of phosphocholine into CDP-choline. The phorbol ester did not stimulate any of the enzyme activities of the ‘de novo’ pathway, whereas oleic acid increased specifically by 2.5-fold the CTP:phosphocholine cytidylyltransferase (CT, EC 2.7.7.15) activity. In addition, no change in the subcellular distribution of CT was observed upon incubation with PMA, in contrast with oleic acid treatment. Cells challenged with oleic acid showed a 25-fold increase in diradylglycerol (DG) content, which was not modified upon incubation with 200 nM PMA, the most effective concentration of phorbol ester promoting choline incorporation. Subcellular fractionation of Krebs-II cells on Percoll gradients revealed that [3H]PMA and 1-radyl-2-[3H]oleoyl-glycerol, derived from exogenously supplied [3H]oleic acid, both exhibited the same enrichment in the endoplasmic reticulum. We have previously shown that the labelled fatty acid also accumulated in the endoplasmic reticulum [Tercé, Record, Tronchère, Ribbes and Chap (1992) Biochem. J. 282, 333-338]. However, PMA induced a stimulation of choline uptake, which was not provoked by PMA 4-O-methyl ether, which interacts poorly with protein kinase C. Our data provide evidence that the enhancement of [3H]choline incorporation into PtdCho triggered by PMA and oleic acid proceeds via completely distinct mechanism(s).

scholarly journals Effect of lipopolysaccharide stimulation on the transcription and translation of messenger RNA for cell surface immunoglobulin M.

1982 ◽  
Vol 156 (4) ◽  
pp. 962-974 ◽  
Author(s):  
D Yuan ◽  
P W Tucker
Keyword(s):  
Messenger Rna ◽  
Fold Increase ◽  
Cell Tumor ◽  
Immunoglobulin M ◽  
Tumor Line ◽  
Surface Immunoglobulin ◽  
Membrane Bound ◽  
Chain Synthesis ◽  
Stimulation Of ◽  
Specific Mrna

Analysis of mu-specific mRNA in the B cell tumor line, BCL1, shows that the cells contain predominantly mRNA for mu chain of membrane-bound immunoglobulin M (IgM) (2.7 kb, mu m mRNA). Stimulation of the cells to Ig secretion by lipopolysaccharide (LPS) results in a 6-12 fold increase in amount of mRNA for the mu chain of secreted IgM (2.4 kb mu s mRNA). The increase in mu s mRNA is accompanied by a 3-4-fold increase in mu m mRNA. The rate of mu chain synthesis of membrane IgM in LPS-stimulated cells is, however, reduced by at least twofold, suggesting that both transcriptional and translational regulatory events are involved in the induction of B lymphocytes to secretion.

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